1. Field of the Invention
This invention relates to the field of safety caps, and in particular to a child-resistant safety cap especially useful for liquid containers, and to a particular liquid container for use with the cap.
2. Prior Art
A wide variety of safety caps are known in which inner and outer caps are made axially separable such that when rotated in a direction that would threadably loosen the cap from its container, axial pressure on the outer cap is necessary to engage an inner cap and thereby remove the cap from the container. These devices have in common the attribute that the inner part of the outer cap is some way spaced from or larger than the outer part of the inner cap. The inner and outer caps are brought together by misaligning the outer cap with respect to the inner cap (e.g., by tilting the outer cap on the inner cap), by axially displacing the outer cap with respect to the inner cap, or by pinching the outer cap to deform the outer cap onto the inner cap. The user is then able to manually engage the inner cap and unthread the inner cap from the container.
A child-resistant cap is unfortunately also sometimes inherently adult resistant as well. Caps that require undue pressure either axially or radially may be too difficult for adults to operate, especially where the adult suffers from an arthritic condition or the like. In many prior art designs, the extent of axial or radial pressure which must be applied to loosen the cap is largely dependent upon how tight the inner cap happens to be threaded down on the container. For example, prior art designs are known with tapered pins, inclined surfaces or rounded pins or bumps. Examples are disclosed in U.S. Pat. Nos. 2,847,139--Christiansson et al (tapered pins); 1,061,214--Sentman (bumped); 4,241,840--Willis (inclined teeth); and 3,888,375 (sloping surfaces). Some of these rely on radial pressure in addition to axial pressure. Substantial axial pressure is required to maintain engagement between the inner and outer caps when the inner cap is threaded tightly on the container.
Prior art caps may have a central pin for centering a part of the outer cap on the inner cap, for example as in 4,353,474--Luker. Such caps typically permit substantial axial misalignment of the inner cap with respect to the bottle, or of the outer cap with respect to the inner cap. The characteristic looseness of these two-part caps frequently aggravates the difficulty of all persons, including adults, in opening the child-resistant cap. The loose feel of easily-misaligned devices offends the user's sense of security when the container is being closed. Inasmuch as these caps are intended to isolate materials that could be dangerous to children, for example drugs, cleaning chemicals and the like, the user is inclined to tighten the closure as securely as reasonably necessary. When the cap feels sloppy and loose, the user is inclined to tighten that much harder, to overcome the lack of security evidenced by the loose feel. Overtightening may result in a very difficult time in opening the container the next time the material therein is needed.
The present invention maintains precise axial alignment between the inner cap and the neck of the bottle by engagements located at two areas spaced along the axis. The inner cap is carried on the container by threads along the container neck, as is conventional. However, the inner cap of the invention is also aligned with respect to the container at the extreme end of a nozzle extending from the threaded part of the container. Therefore, the inner cap remains relatively securely aligned to the bottle even as the inner cap is loosened on the container.
The invention further employs a direction-sensitive engagement structure between the inner and outer cap that is characterized by facing perpendicular surfaces operative in the tightening direction, and sloping surfaces operative in the loosening direction. The sloping surfaces define an incline of from 40 to 70 degrees, preferably about 50 degrees to horizontal, and a perpendicular stop is applied to each sloping surface in loosening the closure. Therefore, when tightening the top down on the container, the user is most secure in that even without axial pressure the outer cap is perpendicularly engaged against the inner cap and the inner cap is precisely and securely aligned with respect to the bottle. The user is not inclined to exert a great deal of effort in overcompensating for perceived looseness and in overtightening the cap. Instead, the user is able to feel the snugness of connection as the cap is fully tightened. Additional engagement structure between the inner cap and a nozzle portion in the neck of the container preferably adds to the user's confidence by providing a tactile indication of full engagement of the inner cap to the neck, and accordingly to the nozzle.
The cap of the invention is preferably used for containers of strong cleaning chemicals such as toilet bowl cleaner. The safety cap is affixed to a nozzle member removably placed in the neck of the bottle, the nozzle having a part defining a liquid conduit extending out of the neck, and also extending downwardly into the container, the conduit being aligned axially along the neck. The neck is provided with a S-shaped bend, the uppermost bend of the S-shape defining the lowermost reach of the nozzle. In use, the user tips the bottle to fill a liquid trap defined by the S-shaped bend. In squeezing the bottle or otherwise extracting the liquid, the user has only to pressurize the charge of material residing in the trap of the S-shape bend. This structure provides additional safety and assurance to the user.
Unlike prior art devices in which a loosely-mounted outer cap is attached to an inner cap by means of an axial pin or similar structure, the present invention has an inner cap attached to a nozzle by such a pin. The inner cap is also, of course, attached to the neck of the container by its threads. Therefore, axial alignment is achieved without the possibility of the pin-supported cap wobbling with respect to the pin, as occurs in prior devices. This additional alignment and security prevents users from inadvertently overtightening the inner cap to overcome a misperceived lack of secure sealing, and later having difficulty or accidents in removing the inner cap.